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R-49 is the common target for the roof or ceiling in cold and mixed climates. That is about 20 inches of blown fibreglass, 15 inches of blown cellulose, 16 inches of fibreglass batt or about 8 inches of closed-cell spray foam. Air seal the ceiling plane before adding any of it.
Acoustic panels needed = wall area × the share to treat ÷ panel size: about 15% of the wall for an office or bedroom, 22% for a media room and 35% for a studio. A 14 × 12 ft room with 8 ft ceilings has 2 × (14 + 12) × 8 = 416 sq ft of wall; at 22% that is about 92 sq ft, or 13 panels of 2 × 4 ft with 10% waste. Panels treat echo; blocking sound takes mass and mineral wool in the cavities, which this sizes too.
With these inputs:
| Result | Value |
|---|---|
| Wall surface area | 416 sq ft |
| Ceiling area | 168 sq ft |
| Acoustic panel coverage | 92 sq ft |
| Panels required | 101 panels |
| Mineral wool batts for cavities | 642 sq ft |
| Expected assembly rating | STC 45–50 |
| Estimated material cost | $939 |
Wall area = 2 × (length + width) × ceiling height · Panel coverage = wall area × treatment percentage for the room type · Panels = coverage × (1 + waste %) ÷ panel square footage
Cavity insulation like mineral wool kills the resonance inside a wall and typically adds 4 to 6 STC points. Big gains come from mass (a second layer of drywall) and decoupling (resilient channel or clips).
Treating 15 to 25% of the wall surface handles most rooms. Studios go to 35%. Start with first reflection points and the wall behind you.
It absorbs airborne sound within the cavity, which helps, but it does not stop sound transmitting through the structure. A wall's sound rating depends far more on mass, decoupling and airtightness than on what is in the bays. Insulation alone typically moves a wall a few STC points — real improvement needs the assembly changed, not just filled.
Soundproofing stops sound passing from one space to another; absorption reduces reflections within a space. Foam panels on a wall make a room sound less echoey — that is absorption — and do essentially nothing for the neighbour hearing you. Confusing the two is the single most common reason a soundproofing project disappoints.
Slightly, at typical densities, and it is easier to friction-fit tightly which matters because gaps leak sound. The difference between the two is small compared with the difference made by decoupling the drywall or adding a second layer with damping compound. Choose on price and handling unless the rest of the assembly is already done properly.
Need the whole roof at once? The free roofing calculator works out roof area, squares, shingle bundles, underlayment, drip edge, ridge cap and installed cost from one set of measurements.